Impact switch



L. ALPERT IMPACT SWITCH June 12, 1962 Filed Feb. 6, 1961 FIG.

if/ gVw all I FIG. 3.

ONITORING Q NDICATOR EXPLOSIVE IN VEN TOR.

SQUIB LOUIS ALPERT HYDROSTAT ENABLING CIRCUIT FIG. 5.

United States Patent Filed Feb. 6, 1961, Ser. No. 87,535 4 Claims. (Cl.HBO-61.45) (Granted under Title 35, US. Code (1952), see. 266) Theinvention described herein may be manufactured and used by or for theUnited States of America for governmental purposes without the paymentof any royalties thereon or therefor.

This invention relates to air dropped underwater ordnance, such as depthcharges, and more particularly to an inertia actuated enabling switch,actuated by water entry impact, employed in a depth charge fuzingsystem.

A relatively new technique of delivering depth charges to submergedtargets, such as enemy submarines, is by rocket motor which carries thedepth charge from a launching ship through an air trajectory ofsubstantial range to the desired point of water entry, exemplary ofwhich is disclosed in the patent application of Saholt et al. for RocketThrown Missile, Serial No. 8,201, filed February 11, 1960. While waterentry impact switches have heretofore been employed with such missilesthey have not been entirely satisfactory due to unreliability,difiiculties encountered in surveillance tests and costs of manufacture.

One of the objects of this invention is to provide a momentary contactimpact switch device which will simultaneously and independentlyenergize a plurality of enabling fuse arming circuits.

Another object is to provide monitoring intelligence for such switchdevice.

Another object is to provide a hermetically sealed switch device whichmay be readily tested without subjecting it to a destructive test.

Further objects are to provide a switch device which is simple inconstruction, economical of manufacture, and highly reliable inoperation.

Still further objects, advantages, and salient features will become moreapparent from the description to follow, the appended claims and theaccompanying drawing in which:

FIG. 1 is a side elevation of a missile employing the subject of theinvention;

FIG. 2 is an enlarged section of the switch device, taken on line 22.,FIG. 1;

FIG. 3 is a section taken on line 33, 2;

FIG. 4 is a section taken on line 44, FIG. 2; and

FIG. 5 is a simplified circuit in which the switch device is employed.

Referring in detail to the drawing, and first to FIG. 1, the subject ofthe invention comprises a switch device 14 carried by a missile 12, suchas a rocket launched depth charge, which is to be actuated at theinstant the missile impacts the surface of the water 14. As best shownin FIGS. 2, 3 and 4, the switch device comprises a plurality of axiallyaligned circular members to, 1d, 20, 22, having central bores 24, 26,28, 30. Member 20 is provided with a circular flange 32 which engagesone end of member 18 and member 22 is provided with a similar flange 34which engages member 29.

A pair of switches S 3 are disposed between members 16, 18, these partsall being secured together by a plurality of screws as which threadedlyengage member 18. A similar switch S is disposed between members 2%, 22and these parts are similarly secured together by screws 38 whichthreadedly engage member 29.

A shaft 46) is supported for axial movement in the 3,038,973 PatentedJune 12, 1962 bores of the various members, the shaft having an affixedweight 42 which is urged rearwardly by a spring 44, the ends of whichabut the weight and a shoulder within member 18. Shaft 4t? is providedwith frusto-conical portions 46, 4-3 which actuate the switches. Theswitches are of the conventional micro-switch type having buttonactuators 50. As shown in FIG. 2, switches S S are open with the buttonssuitably gapped from the actuator shaft and switch S is closed, thebutton having ridden up the conical surface and onto the uniformdiameter portion of the shaft.

The switch actuator parts so far described may be temporarily assembledwithin a suitable cylindrical container and tested for proper operation.In one particular environment the switches must be actuated by the shaftand weight when the impact acceleration is in excess of 60 Gs and notactuate to a 20 G impact shock or when impact shock is not applied alongthe axis of the shaft. When the parts so far described have passed theirinspection test they are then disposed within a cylindrical casing 52. Acup-shaped closure member 54 is then disposed within the casing and itsend 56 is spun over the closure, solder 53 being applied to hermeticallyseal the joint.

The closure member is provided with a central glass portion 6%, suitablyfused or cemented to a metal ring 62, the joint between the ring andclosure being similarly sealed by solder 64. Lead wires 65', a pair foreach switch, terminate at terminals 66, these being hermetically sealedwhere they pass through the glass portion.

The entire casing is next disposed within a cylindrical cavity 63 in thedepth charge, a dimple 7 0 being provided to slide into a groove 72 toorient the terminals in a desired relationship. A ring-shaped nut 74secures the cas ing within the cavity. An electrical insulating plate 76is next appiied and coded wires 78 are attached to the terminals.

In operation, when missile 12 strikes the Water shaft 40 and weight 42move forwardly against the urge of spring 44 and conical portion 46momentarily actuates switches S S simultaneously. As shown in FIG. 5,both switches actuate an enabling switch or circuit which is the firststep in arming the depth charge. When it sinks to desired depth ahydrostat effects operation of a suitable squib which causes detonationof the explosive, these operations being conventional.

During the handling and surveillance of the device, it may be tested atany time by suitable apparatus adapted to produce the impact forceswhich it will experience at water entry to determine operability of thevarious switches. if, for reason during such handling, switch S shouldbecome actuated a monitoring indicator will record such event to thusindicate that the device might be faulty.

Cbviously many modifications and variations of the present invention arepossible in the light of the above teachings. it is therefore to beunderstood that within the scope of the appended claims the inventionmay be practiced otherwise than as specifically described.

What is claimed is:

l. inertia actuated apparatus comprising a shaft mounted for axialmovement and having an inertia weight affixed thereto, a spring urgingsaid shaft in one direction of movement to a predetermined limitposition, a pair of axially spaced conical switch actuating surfaces onsaid shaft, a pair of normally open switches carried by said apparatusadapted to be simultaneously actuated to closed position by one of saidconical surfaces in response to movement of said shaft in its oppositedirection of movement, and a normally open switch carried by saidapparatus adapted to be actuated to open position in response tomovement of said shaft and the other of said conical surfaces in saidopposite direction, said weight and spring being disposed between saidconical surfaces and said conical surfaces being of reducing diameter indirections toward opposite ends of said shaft.

2. Apparatus in accordance with claim 1 wherein the other of saidconical surfaces is disposed adjacent a port-ion of said shaft ofuniform diameter, whereby said shaft may move axially a predeterminedamount before said second switch cooperates with said other conicalsurface.

3. Inertia actuated apparatus comprising a plurality of stackedseparable axially aligned circular disk-lilce members having alignedcentral bores, a shaft supported for axial movement by said bores, afirst annular space between a first and second of said members, a pairof normally open switches disposed within said first space, meanssecuring the first and second of said members and said switch together,an inertia weight affixed to said shaft and disposed within the secondmember, a spring surrounding said shaft urging said weight against athird of said members, a second annular space between the third and afourth of said members, a third switch disposed within said secondspace, means securing the third and fourth members and said third switchtogether, a fifth of said members having an end wall spaced from thefourth of said members, a cup-shaped cylindrical casing telescopicaliycontaining ail of said members having its edge hermetically engagingsaid fifth member and securing all of said members together within same,said shaft having a first conical portion disposed within said firstspace and arranged to simultaneously actuate said pair of switches and asecond conical portion disposed within said second space adapted topermit the third switch to open.

4. Apparatus in accordance with claim 3 wherein said fifth member isprovided with a central portion of electrical insulating material, andterminals extending through said material having their inner endselectrically connected to all of said switches.

Bonnell et al Dec. 9, 1958 Weaver Apr. 11, 1961

